A semiconductor laser is a laser in which a semiconductor material is used as a working substance, has advantages such as a small volume, high efficiency, a simple structure, a relatively long service life, simple modulation, and a relatively low price, and is widely applied in the industry, communication, military, life science, medical treatment.
However, during working of the semiconductor laser, when a part of laser light emitted by the semiconductor laser returns back into the laser chip along the original path, laser power of the semiconductor laser decreases, which affects quality of a laser beam of the semiconductor laser, and burns the diode chip in severe cases, causing the laser to fail. With different chips and different packaging modes, back-reflection light of the semiconductor laser affects a laser beam differently. How to detect influence on a laser beam from back-reflection light is a problem that requires an urgent solution.